I have a field in my database with duplicates. I want to use it in a dropdown list, which has to return distinct data.
Here is the method that I created to do this:
public IEnumerable<SelectListItem> GetBranches(string username)
{
using (var objData = new BranchEntities())
{
IEnumerable<SelectListItem> objdataresult = objData.ABC_USER.Select(c => new SelectListItem
{
Value = c.BRANCH_CODE.ToString(),
Text = c.BRANCH_CODE
}).Distinct(new Reuseablecomp.SelectListItemComparer());
return objdataresult;
}
}
Here is the class I am using:
public static class Reuseablecomp
{
public class SelectListItemComparer : IEqualityComparer<SelectListItem>
{
public bool Equals(SelectListItem x, SelectListItem y)
{
return x.Text == y.Text && x.Value == y.Value;
}
public int GetHashCode(SelectListItem item)
{
int hashText = item.Text == null ? 0 : item.Text.GetHashCode();
int hashValue = item.Value == null ? 0 : item.Value.GetHashCode();
return hashText ^ hashValue;
}
}
}
Nothing is returned and I get the error below. When I try a basic query without Distinct, everything works fine.
{"The operation cannot be completed because the DbContext has been disposed."}
System.Exception {System.InvalidOperationException}
Inner exception = null
How can I return distinct data for my dropdown?
Technically, your problem can be solved simply by appending .ToList() after your Distinct(...) call. The problem is that queries are evaluated JIT (just in time). In other words, until the actual data the query represents is needed, the query is not actually sent to the database. Calling ToList is one such thing that requires the actual data, and therefore will cause the query to be evaluated immediately.
However, the root cause of your problem is that you are doing this within a using statement. When the method exits, the query has not yet been evaluated, but you have now disposed of your context. Therefore, when it comes time to actually evaluate that query, there's no context to do it with and you get that exception. You should really never use a database context in conjuction with using. It's just a recipe for disaster. Your context should ideally be request-scoped and you should use dependency injection to feed it to whatever objects or methods need it.
Also, for what it's worth, you can simply move your Distinct call to before your Select and you won't need a custom IEqualityComparer any more. For example:
var objdataresult = objData.ABC_USER.Distinct().Select(c => new SelectListItem
{
Value = c.BRANCH_CODE.ToString(),
Text = c.BRANCH_CODE
});
Order of ops does matter here. Calling Distinct first includes it as part of the query to the database, but calling it after, as you're doing, runs it on the in-memory collection, once evaluated. The latter requires, then, custom logic to determine what constitutes distinct items in an IEnumerable<SelectListItem>, which is obviously not necessary for the database query version.
I'm very new to breeze/knockout, but I'm 99% of the way to doing what I need to do. I'm using the Hot Towel template, and I'm successfully retrieving a list of items via breeze. The entity (ITBAL) is a database first Entity Framework entity. When I look at the JSON coming back in Fiddler, I see the correct data. The problem is that all of the properties of data.results are dependentobservables, and not the raw values themselves.
We have a custom grid control that is trying to display the data.results array. Because it is not expecting observables, it is simply displaying "function dependentobservable" instead of the value.
I tried to unwrap the object, but keep getting the circular reference error. I don't know why that is, since ITBAL isn't associated with anything.
The data as Fiddler reports it:
[{"$id":"1","$type":"WebUIHtml5HotTowel.Models.ITBAL, WebUIHtml5HotTowel","IBITNO":"A100 ","IBWHID":"1 ","IBITCL":"50","IBITSC":"3 ","IBSUSP":" ","IBVNNO":"100 ","IBPRLC":" ","IBSCLC":" ","IBCCCD":"P","IBPICD":" ","IBSAFL":"Y","IBSTCS":399.99000,"IBUSCS":0.00000,"IBAVCS":414.95214,"IBLCST":7.00000,"IBLCCC":20.0,"IBLCDT":110923.0,"IBLSCC":20.0,"IBLSDT":130111.0,"IBLXCC":19.0,"IBLXDT":990102.0,"IBMXO1":2100.000,"IBMXO2":0.000,"IBMXO3":0.000,"IBMNO1":5.000,"IBMNO2":0.000,"IBMNO3":0.000,"IBFOQ1":0.000,"IBFOQ2":0.000,"IBFOQ3":0.000,"IBOHQ1":327.000,"IBOHQ2":0.000,"IBOHQ3":0.000,"IBAQT1":1576.000,"IBAQT2":0.000,"IBAQT3":0.000,"IBBOQ1":50.000,"IBBOQ2":0.000,"IBBOQ3":0.000,"IBPOQ1":448.000,"IBPOQ2":0.000,"IBPOQ3":0.000,"IBIQT1":1446.000,"IBIQT2":0.000,"IBIQT3":0.000,"IBRMD1":10.000,"IBRMD2":0.000,"IBRMD3":0.000,"IBRYD1":10.000,"IBRYD2":0.000,"IBRYD3":0.000,"IBISM1":0.000,"IBISM2":0.000,"IBISM3":0.000,"IBISY1":0.000,"IBISY2":0.000,"IBISY3":0.000,"IBAMD1":0.000,"IBAMD2":0.000,"IBAMD3":0.000,"IBAYD1":0.000,"IBAYD2":0.000,"IBAYD3":0.000,"IBMMD1":0.000,"IBMMD2":0.000,"IBMMD3":0.000,"IBMYD1":0.000,"IBMYD2":0.000,"IBMYD3":0.000,"IBSMD1":1.0,"IBSMD2":0.0,"IBSMD3":0.0,"IBSYD1":1.0,"IBSYD2":0.0,"IBSYD3":0.0,"IBBLME":335.000,"IBBLYO":2680.000,"IBBLLY":1441.000,"IBNMTY":8.0,"IBNMLY":11.0,"IBQSMD":21.000,"IBQSYD":21.000,"IBQSLY":20.000,"IBISMD":16318.19,"IBISYD":16318.19,"IBISLY":45714.87,"IBCSMD":373.46,"IBCSYD":373.46,"IBCSLY":67.00,"IBDQMD":0.000,"IBDQYD":0.000,"IBDQLY":0.000,"IBDSMD":0.00,"IBDSYD":0.00,"IBDSLY":0.00,"IBDCMD":0.00,"IBDCYD":0.00,"IBDCLY":0.00,"IBNOMD":18.0,"IBNOYD":18.0,"IBNOLY":18.0,"IBPKMD":15.0,"IBPKYD":15.0,"IBPKLY":14.0,"IBINUS":" ","IBIAID":0.0,"IBSAID":0.0,"IBCQT1":1527.000,"IBCQT2":0.000,"IBCQT3":0.000,"IBFCST":"Y","IBDRSH":" ","IBWMIU":"JP","IBFL15":" ","IBUS20":" ","IBLPR1":0.00000,"IBLPR2":0.00000,"IBLPR3":0.00000,"IBLPR4":0.00000,"IBLPR5":0.00000,"IBLPCD":" ","IBABCC":"B","IBPRCL":0.0,"IBQBCL":" ","IBACDC":"Y","IBTDCD":" ","IBDOUM":" ","IBTP01":0.0,"IBTP02":0.0,"IBTP03":0.0,"IBTP04":0.0,"IBLMCC":20.0,"IBLMDT":130513.0,"IBTMPH":"Y","IBCOMC":" ","IBCOMF":0.00000,"IBITCT":" ","IBEOQT":0.000,"IBITCM":0.0,"IBBRVW":" ","IBPTID":" ","IBQTLT":0.0000,"IBCTY1":"AUS","IBCTY2":"AUS","IBTXCD":"1","IBREVS":"Y","IBITXC":" ","IBMNOQ":0.000,"IBSTUS":0.000,"IBUS30":" ","IBPSLN":" ","IBPLIN":"N","IBUPDP":"Y","IBDFII":"2011-08-11T00:00:00.000","IBLHRK":"A","IBPLNC":" "}]
My Controller:
[BreezeController]
public class ItemInquiryController : ApiController
{
readonly EFContextProvider<AplusEntities> _contextProvider = new EFContextProvider<AplusEntities>();
[System.Web.Http.HttpGet]
public string Metadata()
{
return _contextProvider.Metadata();
}
[HttpGet]
public IQueryable<ITBAL> ItemBalances(string itemNumber, string warehouse)
{
return _contextProvider.Context.ITBALs.Where(i => i.IBITNO == itemNumber && i.IBWHID == warehouse)
.OrderBy(i => i.IBWHID)
.ThenBy(i => i.IBITNO);
}
}
The relevant portion from the viewmodel:
var manager = new breeze.EntityManager("api/ItemInquiry");
var store = manager.metadataStore;
var itbalInitializer = function (itbal) {
itbal.CompositeKey = ko.computed(function () {
return itbal.IBITNO() + itbal.IBWHID();
});
};
store.registerEntityTypeCtor("ITBAL", null, itbalInitializer);
var index = "0" + (args.pageNum * args.pageSize);
var query = new breeze.EntityQuery("ItemBalances")
.withParameters({ itemNumber: "A100", warehouse: "1" })
.take(args.pageSize);
if (index > 0) {
query = query.skip(index);
}
manager.executeQuery(query).then(function (data) {
vm.itbals.removeAll();
var itbals = data.results;//[0].Data;
itbals.forEach(function (itbal) {
vm.itbals.push(itbal);
});
vm.totalRecords(1);
itemBalancesGrid.mergeData(vm.itbals(), args.pageNum, parseInt(vm.totalRecords()));
}).fail(function (e) {
logger.log(e, null, loggerSource, true, 'error');
});
I figure I must be missing something fairly simple, but it is escaping me.
UPDATE: I removed the BreezeController attribute from the ApiController, and it works correctly.
Jon, removing the [Breeze] attribute effectively disables breeze for your application so I don't think that is the long term answer to your problem.
If you don't actually want entities for this scenario - you just want data - than a Breeze projection that mentions just the data to display in the grid would seem to be the best choice. Projections return raw data that are not wrapped in KO observables and are not held in the Breeze EntityManager cache.
If you want the data as cached entities and you also want to display them in a grid that doesn't like KO observable properties ... read on.
You can unwrap a KO'd object with ko.toJS. However, the grid is likely to complain about circular references (or throw an "out of memory" exception as some grids do) ... even if the entity has no circular navigation paths. The difficulty stems from the fact that every Breeze entity has an inherent circularity by way of its entityAspect property:
something.entityAspect.entity //'entity' points back to 'something'
Because you are using Knockout for your model library and because you say ITBAL has no navigation properties ("is not related to anything"), I think the following will work for you:
manager.executeQuery(query).then(success) ...
function success(data) {
var unwrapped = ko.toJS(data.results).map(
function(entity) {
delete entity.entityAspect;
return entity;
});
vm.itbals(unwrapped);
vm.totalRecords(1); // huh? What is that "parseInt ..." stuff?
itemBalancesGrid.mergeData(vm.itbals(), args.pageNum, parseInt(vm.totalRecords()));
})
ko.toJS is a Knockout function that recursively unwraps an object or collection of objects, returning copies of values. Then we iterate over the copied object graphs, deleting their entityAspect properties. The array of results is stuffed into the vm.itbals observable and handed along.
You can imagine how to generalize this to remove anything that is giving you trouble.
Extra
What the heck is vm.totalRecords? I sense that this is supposed to be the total number of matching records before paging. You can get that from Breeze by adding .inlineCount() to the breeze query definition. You get the value after the query returns from the data.inlineCount property.
Do you really need vm.itbals()? If all you do here is pass values to the grid, why not do that and cut out the middle man?
The following success callback combines these thoughts
function success(data) {
var unwrapped = ko.toJS(data.results).map(
function(entity) {
delete entity.entityAspect;
return entity;
});
itemBalancesGrid.mergeData(unwrapped, args.pageNum, data.inlineCount);
})
I have a very strange issue that I cannot explain. I have my base mapping with this
//This will automatically cast the row into the correct object type based on the value in AccountType
DiscriminateSubClassesOnColumn<string>("AccountType")
.Formula(String.Format("CASE AccountType WHEN {0} THEN '{1}' WHEN {2} THEN '{3}' ELSE '{4}' END",
(int)PaymentMethodType.CheckingAccount,
typeof(ACH).Name,
(int)PaymentMethodType.SavingsAccount,
typeof(ACH).Name,
typeof(CreditCard).Name));
I have looked in the logs, I have executed the sql that nhibernate is generating, and all records have the same data. There is not difference in them that would denote why this should not work.
The base class is PaymentMethodBase. I have 2 subclasses, CreditCard and ACH, which inherit from PaymentMethodBase.
Then, I have this extension
public static string PaymentMethodName(this PaymentMethodBase paymentMethod)
{
if (paymentMethod is ACH)
{
var ach = (ACH)paymentMethod;
return String.Format("{0} {1}", ach.BankName, String.Format("XXXX{0}", ach.AccountNumber.Substring(ach.AccountNumber.Length - 4)));
}
if (paymentMethod is CreditCard)
{
var creditCard = (CreditCard)paymentMethod;
return String.Format("{0} {1}", creditCard.Name, creditCard.CreditCardNumber);
}
return "Unknown Payment Method";
}
Which I call like this.
public SelectList PaymentMethodsSelectList
{
get
{
var methods = (from p in PaymentMethods
where p != null
select new
{
id = p.PaymentMethodId,
name = p.PaymentMethodName()
}).OrderBy(x => x.name);
var results = methods.ToList();
results.Insert(0, new { id = (int)NewPaymentMethods.ACH, name = "<New eCheck Account...>" });
results.Insert(0, new { id = (int)NewPaymentMethods.CreditCard, name = "<New Credit Card...>" });
return new SelectList(results, "id", "name");
}
}
This code is used by 2 models. The collection of payment methods are all coming from the same object - a customer object. The collection is mapped like this.
HasMany<PaymentMethodBase>(x => x.PaymentMethods)
.KeyColumn("CustomerId")
.Where(y => y.AccountType < 10)
.Inverse()
.Cascade.All();
So, I get the customer 2 different ways. One is that I get the customer through another object (main site). The other has the object being pulled directly by id (in an iframe). The direct by id method works every time. The other method, where I get the customer through another object, causes only the first and last payment method to cast correctly. If there are more than 2, they are left in the base class and appear in the middle of the list after the sort.
I have tried changing the parent object to just mapping the id and then getting the customer record by the ID. Failure. There is something else in the way that is causing this to happen, but only on that one model.
I suspect that the issue here is Fetching issue.
Since the extension method is running on the .Net side rather than in the "NHibernate level" it cannot run properly when the collection of payment methods is not available.
Perhaps in the direct by Id methos you have Fetching set up for the payments whereas in the indirect method the automatic fetching goes only to the Customer object but stops short before fetching the Payment methods.
Try to instruct NHibernate to pre-fetch the Payment methods for you in the indirect method.
Something like:
Session.Query<SomeObject>.Where(.....).Fetch(x => x.Customer).ThenFetch(c => c.PaymentMethods)
The problem here appeared to be the usage of extension methods within a linq statement to return a value based on the type. The issue is that it would work some places but not others, probably due to some fetching issue, as suggested by Variant.
I solved this problem by making a property in my base class like this
public virtual string DisplayName { get { return "Unknown"; } }
Then I overrode the property in my child class and added the logic that was in the extension method for that type.
public override string DisplayName { get { return String.Format("{0} {1}", Name, AccountMask); } }
I am trying to load a sortable jqgrid 3.5 from a query with multiple joins in it and having much difficulty as I am a novice with both Linq and jqgrid. In order to allow for sorting I first was attempting to load it using dynamic SQL.
Since I am pulling columns from multiple tables I assume my return will be a class object which I will populate (or will it be a table). How can I return a IQueryable custom class object when using dynamic SQL with multiple .JOIN clauses. If this is impossible how do I return IQueryable data from a stored procedure call. It is easy to create dynamic SQL in the stored procedure - I am unsure how to load my grid with it however.
Sorry if this is all over the place but I can't seem to find a way. If you can recommend the most straight forward way to load my sortable grid from a query which has multiple joins in I am much appreciated.
My controller code:
public ActionResult GridData(string sidx, string sord, int page, int rows)
{
EquipTrak eqt = new EquipTrak();
var equipment = eqt.GetGridEquipment(sidx, sord);
var dataJson = new
{
total = 10000,
page = 1,
records = 10000,
rows = (from e in equipment
select new
{
equip_id = e.equip_id,
cell = new string[] {
e.equip_id,
e.equipType,
e.makeType,
String.Format("{0:MM/dd/yyyy}", e.serv_due_dt)
}
}).ToArray()
};
return Json(dataJson);
}
}
my class code (incomplete):
namespace ULS_Site.Models
{
public class EquipTrak
{
uls_dbDataContext ulsDB = new uls_dbDataContext();
public IQueryable<equipmentCls> GetGridEquipment(string sidx, string sord)
{
try
{
return
Not sure if this is the best or worst solution but I used SQL Server views to handle all the joining required. I could then use .Orderby and .Where against the view which was in my data context.